Power Supply Apparatus and Power System

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2025-022515, filed on February 14, 2025, the entire contents of which are incorporated herein by reference.

Embodiments described herein relate generally to a power supply apparatus and a power system.

Conventionally, various techniques have been known, in which a battery provided in electric vehicles (EVs), plug-in hybrid electric vehicles (PHEVs), or other electric vehicles is charged, by using commercial power supplied from a power grid such as that of a residence, or discharged so that the discharged power can utilized as a power source for the residence.

200 100 In a consumer receiving power supply from a single-phase, three-wire power grid of a residence or the like, both a single-phaseV between a pair of voltage lines and a single-phaseV between either one line of the pair of voltage lines and a neutral line, are utilized via a distribution board.

200 100 Under these circumstances, even if a single-phaseV is supplied between the pair of voltage lines of the consumer from an on-board charger using power of an on-board battery of the vehicle, the potential of the neutral line becomes undefined or floating at the consumer's residence, preventing the voltage between the voltage line and neutral line from being used as the single-phaseV.

200 100 There is a known charging/discharging system that functionally grounds the neutral point of the power conversion unit to the chassis potential, enabling a power storage device to be used as a power source in a case where power is not supplied from either the single-phaseV or single-phaseV power grids (See, for example, Patent Literature JP 2014-060834 A).

However, under the standards for on-board chargers, the neutral point of the power conversion unit is not allowed to be functionally grounded to the chassis potential. This leaves room for improvement in the utilization of an on-board battery as a power source by a consumer receiving power supply from a single-phase three-wire power grid.

A power supply apparatus according to one aspect of the present disclosure includes a charge/discharge cable to which a vehicle is connected, a grid-side switch, an islanded-side switch, and a second control circuit. The charge/discharge cable includes a pair of power lines, a protective earth line at ground potential, and a control line. The grid-side switch is provided between a grid-side input/output end and the charge/discharge cable. The grid-side input/output end is electrically connected to a power grid via a first distribution board. The islanded-side switch is provided between an output end for islanded operation and the charge/discharge cable. The output end for islanded operation is electrically connected to a second distribution board different from the first distribution board. The second control circuit is configured to control operations of the grid-side switch and the islanded-side switch, and communicate, via the control line, with a first control circuit of a power conversion device provided in the vehicle. A pair of voltage lines of the grid-side input/output end is electrically connected to a pair of power lines of the charge/discharge cable via the grid-side switch. A pair of voltage lines of the output end for islanded operation is electrically connected to the pair of power lines of the charge/discharge cable via the islanded-side switch. The pair of power lines of the charge/discharge cable is electrically connected to a pair of power lines of an AC-side input/output end of the power conversion device in the vehicle. The AC-side input/output end serves to input and output AC power. A neutral line of the grid-side input/output end and the protective earth line of the charge/discharge cable are connected to ground potential. The second control circuit is configured to, when the vehicle is connected via the charge/discharge cable, establish conduction between the first distribution board and the charge/discharge cable by turning on the grid-side switch, and control a grid-connected supply operation or a grid-interconnection operation while keeping the conduction between the first distribution board and the charge/discharge cable. The grid-connected supply operation is operation in which AC power at a first voltage supplied from the power grid via the first distribution board is supplied to the vehicle. The grid-interconnection operation is operation in which AC power at the first voltage supplied from the vehicle via the charge/discharge cable is supplied to the first distribution board. The second control circuit is configured to, when a power failure of the power grid is detected, establish conduction between the second distribution board and the charge/discharge cable by turning on the islanded-side switch, output a control signal instructing the islanded operation to the first control circuit of the power conversion device while keeping the conduction between the second distribution board and the charge/discharge cable, and control islanded operation in which AC power supplied from the vehicle via the charge/discharge cable is supplied to the second distribution board. The control signal instructing the islanded operation specifies, as an output voltage value, a second voltage that is a potential difference between each line of the pair of voltage lines of the grid-side input/output end and the neutral line of the grid-side input/output end in the grid-connected supply operation or the grid-interconnection operation.

Embodiments of a power conversion device (on-board charger), vehicle, power supply apparatus, and power system according to the present disclosure will be described below with reference to the drawings.

Note that in the description of the present disclosure, components having the same or substantially the same function as those previously described with reference to preceding drawings are denoted by the same reference numerals, and their description may be omitted as appropriate. Even in representing the same or substantially the same components, the dimensions and ratios may differ among drawings. In addition, for example, to ensure the visibility of the drawings, only major components may be denoted by reference numerals in the description of each drawing, and even if components having the same or substantially the same function as those described with reference to the preceding drawings are illustrated, reference numerals may not be provided thereto.

Note that in the description of the present disclosure, components having the same or substantially the same function may be distinguished by appending alphanumeric characters and/or symbols to the ends of the reference numerals. Alternatively, in the case where multiple components having the same or substantially the same function are not to be distinguished, such alphanumeric characters and/or symbols appended to the ends of the reference numerals may be omitted, and the components may be collectively denoted.

1 2 FIGS.and 1 FIG. 2 FIG. 1 2 FIGS.and 1 2 2 a b are diagrams illustrating an exemplary configuration of a power systemaccording to a first embodiment.illustrates an example in a case where a first vehicleis connected.illustrates an example in a case where a second vehicleis connected. Moreover,illustrate a connection state of each of the grid-connected supply operation and grid-interconnection operation.

1 2 FIGS.and 1 2 4 61 62 100 7 200 7 100 7 200 7 a b c d As illustrated in, the power systemincludes a vehicle, an electric vehicle supply equipment (EVSE), a distribution board, a critical load distribution board, aV load, aV load, aV critical load, and aV critical load.

1 9 1 9 1 200 9 200 100 The power systemis electrically connected to a grid. The power systemis a single-phase, three-wire system that receives AC power from the grid. In the present disclosure, the power systemis supplied with single-phaseV AC power from the grid, with a potential difference between a pair of voltage lines being single-phaseV and a potential difference between one line of the pair of voltage lines and the neutral line being single-phaseV.

9 9 1 200 The gridis a power grid that transmits AC power (e.g., commercial power) from power facilities such as power plants and substations and supplies the AC power to consumers such as residences. Moreover, the AC power supplied from the gridto power systemis not limited to single-phaseV, and can be other AC power such as single-phase 240 V.

2 2 22 2 The vehicleis, by way of example, an electric vehicle (EV), a plug-in hybrid electric vehicle (PHEV), or other electric vehicles. In this example, the vehicleaccording to the present embodiment is an example of a mobile body. The mobile body can be any type of mobile body configured to be driven by power from a high-voltage battery, such as a passenger car, cargo vehicle, van, motorcycle, electric kick scooter, ship, aircraft, construction machinery, or agricultural machinery. Moreover, the technology according to the present embodiment is not limited to mobile bodies such as the vehicle, but can also be applied to various power conversion devices installed in, for example, amusement facilities or uninterruptible power supplies.

1 2 FIGS.and 2 21 22 23 As illustrated in, the vehiclehas a bidirectional charger, the high-voltage battery, and a charge/discharge socket.

21 22 23 21 20 23 1 2 21 20 22 a b The bidirectional chargeris electrically connected between the high-voltage batteryand the charge/discharge socket. The bidirectional chargerhas an AC-side input/output endelectrically connected to the charge/discharge socketvia a pair of power lines Land L, a protective earth (PE) line, and a control pilot (CP) line. The bidirectional chargerhas a DC-side input/output endelectrically connected to the high-voltage batteryvia a pair of power lines.

21 2 1 2 In this example, the bidirectional chargeris a charger (on-board charger) installed in the vehicleand is an example of a power conversion device. In addition, each of the pair of power lines Land Lis an example of a voltage line through which a single-phase current flows. Additionally, the control pilot line (CP) is an example of a control line.

1 2 FIGS.and 21 211 212 211 As illustrated in, the bidirectional chargerincludes a control unitand a power conversion unit. In this example, the control unitis an example of a first control circuit.

211 21 211 212 211 212 211 212 4 a The control unitis an integrated circuit (IC) for control configured to control the operation of each component of the bidirectional charger. The control unitis electrically connected to the power conversion unitvia a control line. The control unitcontrols the operation of the power conversion unit. For example, the control unitcontrols the operation of the power conversion unitin accordance with a control signal received from an EVSEvia the control pilot line.

211 211 212 20 20 1 2 20 212 200 20 22 a b a b In one example, the control unitcontrols grid-connected supply operation. In the grid-connected supply operation, the control unitcauses the power conversion unitto convert AC power input from the AC-side input/output endinto DC power and output the DC power from the DC-side input/output end. In the grid-connected supply operation, the potential difference between the pair of power lines Land Lat the AC-side input/output endof the power conversion unitis, for example, single-phaseV, which is an example of a first voltage. The DC power output from the DC-side input/output endis supplied to the high-voltage battery.

211 211 212 22 20 20 1 2 20 212 200 20 4 49 b a a a a In one example, the control unitcontrols grid-interconnection operation. In the grid-interconnection operation, the control unitcauses the power conversion unitto convert DC power input from the high-voltage batteryvia the DC-side input/output endinto AC power and output the AC power from the AC-side input/output end. In the grid-interconnection operation, the potential difference between the pair of power lines Land Lat the AC-side input/output endof the power conversion unitis, for example, single-phaseV, which is an example of the first voltage. The AC power output from the AC-side input/output endis supplied to the EVSEvia a charge/discharge cable.

212 211 212 200 200 200 20 21 200 20 21 a b a a b b The power conversion unitoperates under the control of the control unit. The power conversion unitincludes an AC-side input/output endand a DC-side input/output end. The AC-side input/output endis electrically connected to the AC-side input/output endof the bidirectional charger. The DC-side input/output endis electrically connected to the DC-side input/output endof the bidirectional charger.

200 200 212 200 200 200 200 a b a b a b The AC-side input/output endinputs and outputs AC power. The DC-side input/output endinputs and outputs DC power. The power conversion unitconverts power input from either of the AC-side input/output endor the DC-side input/output endinto AC or DC power, and outputs the converted power from the other input/output end of either the AC-side input/output endor the DC-side input/output end.

1 FIG. 2 FIG. 21 2 213 21 2 2 2 213 2 2 213 a b a b As illustrated in, the bidirectional chargerin the first vehiclefurther includes a neutral point connection switch. On the other hand, as illustrated in, the bidirectional chargerin the second vehicledoes not include a neutral point connection switch. In other words, the first vehicleis a vehicleprovided with the neutral point connection switch. Similarly, the second vehicleis a vehiclenot provided with a neutral point connection switch.

213 211 2 213 1 2 200 212 213 1 2 20 212 a a a The neutral point connection switchoperates under the control of the control unitof the first vehicle. The neutral point connection switchis provided between a neutral point NP of a pair of power lines Land Lat the AC-side input/output endof the power conversion unitand a functional grounding line FG at a chassis potential. The neutral point connection switchswitches between conduction and disconnection between the neutral point NP of the pair of power lines Land Lat the AC-side input/output end0of the power conversion unitand the functional grounding line FG at the chassis potential.

2 23 213 1 2 200 212 213 1 2 200 212 a a a In this example, in the first vehicle, the functional grounding line FG at the chassis potential is electrically connected to a protective earth terminal of the charge/discharge socketvia a protective earth line PE. In other words, the neutral point connection switchis provided between the neutral point NP of the pair of power lines Land Lat the AC-side input/output endof the power conversion unitand the protective earth line PE. Additionally, the neutral point connection switchalso switches between conduction and disconnection between the neutral point NP of the pair of power lines Land Lat the AC-side input/output endof the power conversion unitand the protective earth line PE.

211 2 213 211 2 213 a a The control unitof the first vehicleis electrically connected to the neutral point connection switchvia a control line. The control unitof the first vehiclefurther controls the operation of the neutral point connection switch.

211 2 213 200 211 2 212 200 200 a a a a b In one example, in the grid-connected supply operation, the control unitof the first vehicleturns off the neutral point connection switchto establish a state that the neutral point NP of the AC-side input/output endis cut off from the protective earth line PE. In this state, the control unitof the first vehiclecauses the power conversion unitto convert the AC power input from the AC-side input/output endinto DC power and output the DC power from the DC-side input/output end.

211 2 213 200 211 2 212 200 200 a a a b a In one example, in the grid-interconnection operation, the control unitof the first vehicleturns off the neutral point connection switchto establish a state that the neutral point NP of the AC-side input/output endis cut off from the protective earth line PE. In this state, the control unitof the first vehiclecauses the power conversion unitto convert the DC power input from the DC-side input/output endinto AC power and output the AC power from the AC-side input/output end.

3 4 FIGS.and 4 211 2 213 211 2 213 200 211 2 212 200 200 a a a a a b a In one example, in a case where islanded operation (see) is instructed by a control signal from the external EVSE, the control unitof the first vehicleturns on the neutral point connection switch. In other words, in the islanded operation, the control unitof the first vehicleturns on the neutral point connection switchto establish a conductive state between the neutral point NP of the AC-side input/output endand the protective earth line PE. In this state, the control unitof the first vehiclecauses the power conversion unitto convert the DC power input from the DC-side input/output endinto AC power and output the AC power from the AC-side input/output end.

4 21 200 1 2 40 4 1 2 200 212 2 200 1 2 0 2 21 2 200 a a a a a a a The control signal instructing the islanded operation from the external EVSEinstructs the bidirectional chargerto use, as an output voltage value, single-phaseV (first voltage), which is the potential difference between a pair of voltage lines Land Lat a grid-side input/output endof the EVSEin the grid-connected supply operation or grid-interconnection operation. In other words, in the islanded operation, the potential difference between the pair of power lines Land Lat the AC-side input/output endof the power conversion unitof the first vehicleis single-phaseV (first voltage). Thus, in the islanded operation, the potential difference between the pair of power lines Land Lat the AC-side input/output endof the bidirectional chargerof the first vehicleis single-phaseV (first voltage).

213 212 1 2 200 212 2 1 2 200 100 a a a Further, in the islanded operation, the neutral point connection switchis turned on. Thus, the AC power output from the power conversion unitis AC power generated based on the neutral point NP. Accordingly, in the islanded operation, the potential difference between each of the pair of power lines Land Lat the AC-side input/output endof the power conversion unitof the first vehicleand the neutral point NP of the pair of power lines Land Lat the AC-side input/output endis single-phaseV (second voltage).

20 21 2 200 1 2 100 1 2 21 2 4 1 2 49 200 100 2 213 9 2 213 100 200 9 a a a a a a In this way, in the islanded operation, the AC power output from the AC-side input/output endof the bidirectional chargerof the first vehicleincludes single-phaseV (first voltage), which is the potential difference between the pair of power lines Land L, and single-phaseV (second voltage), which is the potential difference between each of the pair of power lines Land Land the neutral point NP. In other words, in the islanded operation, the AC power supplied from the bidirectional chargerof the first vehicleto the EVSEvia a pair of power lines Land Lof the charge/discharge cableis single-phaseV (first voltage) AC power from which single-phaseV (second voltage) is capable of being extracted relative to the protective earth line PE. Thus, the first vehicleequipped with the neutral point connection switchis capable of appropriately determining the potential of the neutral line N at the consumer receiving power from the single-phase three-wire gridin the islanded operation for supplying power to the consumer. In other words, the islanded operation by the first vehicleequipped with the neutral point connection switchenables both single-phaseV device and single-phaseV device to be used by the consumer receiving power from the single-phase three-wire grid.

22 200 212 20 21 22 4 21 22 2 4 22 22 200 212 b b a a b The high-voltage batteryis electrically connected to the DC-side input/output endof the power conversion unitvia the DC-side input/output endof the bidirectional charger. The high-voltage batterystores power supplied from the EVSEvia the bidirectional charger. The high-voltage batteryonly needs to be capable of storing power for driving a traveling motor (main drive motor) provided in the vehicleor for supplying power (discharging) to the external EVSEAny suitable battery, such as a lithium-ion battery, nickel-hydrogen battery, or all-solid-state battery, can be used as the high-voltage battery. In this example, the high-voltage batteryis an example of an on-board battery and is an example of a battery electrically connected to the DC-side input/output endof the power conversion unit.

23 2 49 23 21 4 2 23 a The charge/discharge socketis a power socket provided in the vehiclefor charging and/or discharging. The charge/discharge cableis detachably connected to the charge/discharge socket. The bidirectional chargeris capable of being connected to external power equipment and/or an external load such as the EVSEvia a power socket for charging and discharging that is provided at a position available from outside the vehicle. The charge/discharge socketincludes a pair of power terminals, a protective earth terminal, and a control terminal.

2 2 23 1 2 200 212 23 1 2 49 2 a b a In both the first vehicleand the second vehicle, the pair of power terminals of the charge/discharge socketare electrically connected to the pair of power lines Land Lof the AC-side input/output endof the power conversion unit. In addition, the pair of power terminals of the charge/discharge socketare also electrically connected to the pair of power lines Land Lof the charge/discharge cableconnected to the vehicle.

23 2 2 23 49 2 a b The protective earth terminal of the charge/discharge socketis electrically connected to the functional grounding line FG at the chassis potential in both the first vehicleand the second vehicle. In addition, the protective earth terminal of the charge/discharge socketis also electrically connected to the protective earth line PE of the charge/discharge cableconnected to the vehicle.

2 23 200 212 213 a a Further, in the first vehicle, the protective earth terminal of the charge/discharge socketis electrically connected to the neutral point NP of the AC-side input/output endof the power conversion unitvia the neutral point connection switch.

2 2 23 211 23 49 2 23 4 49 a b a In both the first vehicleand the second vehicle, the control terminal of the charge/discharge socketis electrically connected to the control unit. Additionally, the control terminal of the charge/discharge socketis also electrically connected to the control pilot line CP of the charge/discharge cableconnected to the vehicle. The control terminal of the charge/discharge socketinputs a control signal from the external EVSEvia the charge/discharge cable.

4 4 4 2 49 4 40 2 1 2 49 40 4 61 1 2 4 40 62 1 2 a a a b a a a c The EVSEaccording to the first embodiment is an example of the EVSEaccording to the present disclosure. The EVSEis a power supply apparatus that is electrically connected to the vehiclevia the charge/discharge cable. In the EVSE, a vehicle-side input/output endis electrically connected to the vehiclevia the pair of power lines Land L, the protective earth line PE, and the control pilot line CP of the charge/discharge cable. The grid-side input/output endof the EVSEis electrically connected to the distribution boardvia a pair of power lines Land Land the neutral line N. In the EVSE, an output endfor islanded operation is electrically connected to the critical load distribution boardvia a pair of power lines Land Land a neutral line N.

4 9 61 2 49 4 2 49 100 7 200 7 100 7 200 7 61 4 2 49 100 7 200 7 62 4 2 49 9 a a a b c d a c d a In the grid-connected supply operation, the EVSE, which receives AC power from the gridvia the distribution board, supplies the received AC power to the vehiclevia the charge/discharge cable. In the grid-interconnection operation, the EVSEsupplies the AC power, which is received from the vehiclevia the charge/discharge cable, to theV load, theV load, theV critical load, and theV critical loadvia the distribution board. In the islanded operation, the EVSEsupplies the AC power, which is received from the vehiclevia the charge/discharge cable, to theV critical load, and theV critical loadvia the critical load distribution board. Moreover, in the grid-interconnection operation, the EVSEmay also supply the AC power received from the vehiclevia the charge/discharge cableto the grid.

1 2 FIGS.and 4 41 42 43 42 43 a As illustrated in, the EVSEincludes a control unit, a grid-side relay, and an islanded-side relay. In this example, the grid-side relayis an example of a grid-side switch. In addition, the islanded-side relayis an example of an islanded-side switch.

41 4 41 211 2 49 41 211 2 41 42 43 41 42 43 41 4 a a The control unitis an integrated circuit (IC) for control configured to control the operation of each component of the EVSE. The control unitis electrically connected to the control unitof the vehiclevia the control pilot line CP of the charge/discharge cable. The control unitcommunicates with the control unitof the vehicle. Additionally, the control unitis also electrically connected to the grid-side relayand the islanded-side relayvia a control line. The control unitcontrols the operation of each of the grid-side relayand the islanded-side relay. In this example, the control unitof the EVSEis an example of a second control circuit.

41 2 49 41 42 61 49 41 9 61 2 49 In one example, the control unitcontrols the grid-connected supply operation. In the grid-connected supply operation, in a case where the vehicleis connected via the charge/discharge cable, the control unitturns on the grid-side relayto establish electrical conduction between the distribution boardand the charge/discharge cable. Additionally, in this state, the control unitsupplies the AC power, which is supplied from the gridvia the distribution board, to the vehicleto which the charge/discharge cableis connected.

41 2 49 41 42 61 49 41 2 49 61 In one example, the control unitcontrols the grid-interconnection operation. In the grid-interconnection operation, in a case where the vehicleis connected via the charge/discharge cable, the control unitturns on the grid-side relayto establish electrical conduction between the distribution boardand the charge/discharge cable. Additionally, in this state, the control unitsupplies the AC power, which is supplied from the vehiclevia the charge/discharge cable, to the distribution board.

9 41 2 9 41 2 49 213 In one example, in a case where a power failure of the gridis detected, the control unitcontrols the islanded operation performed by the vehicle. In the islanded operation, in a case where a power failure of the gridis detected, the control unitchecks whether the vehicleconnected via the charge/discharge cableis provided with the neutral point connection switch.

2 49 2 213 41 43 62 49 41 211 21 2 49 41 2 49 62 a a a If the vehicleconnected via the charge/discharge cableis the first vehicleequipped with the neutral point connection switch, the control unitturns on the islanded-side relayto establish electrical conduction between the critical load distribution boardand the charge/discharge cable. Additionally, in this state, the control unitoutputs a control signal instructing the islanded operation to the control unitof the bidirectional chargerinstalled in the first vehicleconnected via the charge/discharge cable. The control unitthen supplies the AC power, which is supplied from the first vehiclevia the charge/discharge cable, to the critical load distribution board.

2 49 2 213 41 41 2 49 213 b If the vehicleconnected via the charge/discharge cableis the second vehiclenot equipped with the neutral point connection switch, the control unitdoes not output a control signal instructing the islanded operation. In other words, the control unitdoes not allow the islanded operation if the vehicleconnected via the charge/discharge cableis not equipped with the neutral point connection switch.

41 411 9 9 41 411 The control unitincludes a backup power supply. In a case where the power supply from the gridis stopped, such as during a power failure of the grid, the control unitis capable of operating using power from the backup power supply.

42 40 4 40 42 61 49 42 61 49 42 1 40 1 40 42 2 40 2 d 40 40 4 40 a a b a b a b a a b The grid-side relayis provided between the grid-side input/output endof the EVSEand the vehicle-side input/output end. In other words, the grid-side relayis provided between the distribution boardand the charge/discharge cable. The grid-side relayswitches between conduction and disconnection between the distribution boardand the charge/discharge cable. Specifically, the grid-side relayswitches between conduction and disconnection between the power line L(voltage line) of the grid-side input/output endand the power line Lof the vehicle-side input/output end. In addition, the grid-side relayswitches between conduction and disconnection between the power line L(voltage line) of the grid-side input/output endand the power line Lof the vehicle-side input/output en. Moreover, the neutral line N of the grid-side input/output endof the EVSEand the protective earth line PE of the vehicle-side input/output endare electrically connected to a grounding line at ground potential.

43 40 4 40 43 62 49 43 62 49 43 1 40 1 40 43 2 40 2 40 43 40 40 c a b c b c b c b The islanded-side relayis provided between the output endfor islanded operation of the EVSEand the vehicle-side input/output end. In other words, the islanded-side relayis provided between the critical load distribution boardand the charge/discharge cable. The islanded-side relayswitches between conduction and disconnection between the critical load distribution boardand the charge/discharge cable. Specifically, the islanded-side relayswitches between conduction and disconnection between the power line L(voltage line) of the output endfor islanded operation and the power line Lof the vehicle-side input/output end. In addition, the islanded-side relayswitches between conduction and disconnection between the power line L(voltage line) of the output endfor islanded operation and the power line Lof the vehicle-side input/output end. Additionally, the islanded-side relayswitches between conduction and disconnection between the neutral line N of the output endfor islanded operation and the protective earth line PE (and the grounding line at ground potential) of the vehicle-side input/output end.

61 9 4 61 61 61 100 7 200 7 100 7 100 61 200 7 200 61 61 61 a a b a b 1 2 FIGS.and The distribution boardis provided between the gridand the EVSE. At least one load is capable of being electrically connected to the distribution board. The loads electrically connected to the distribution boardare capable of operating using AC power supplied from the distribution board.illustrate theV loadand theV loadas examples of at least one load. TheV loadis an electric power device that operates using single-phaseV AC power from the distribution board. TheV loadis an electric power device that operates using single-phaseV AC power from the distribution board. In one example, AC power from the distribution boardcan be supplied to each load in a residence (consumer) via an outlet inside the residence. In this example, the distribution boardis an example of a first distribution board.

62 61 4 62 9 61 62 2 4 62 9 62 62 100 7 200 7 100 7 100 62 200 7 200 62 62 62 a a c d c d 1 2 FIGS.and The critical load distribution boardis provided between the distribution boardand the EVSE. In other words, the critical load distribution boardis electrically connected to the gridvia the distribution board. At least one critical load can be electrically connected to the critical load distribution board. In this example, the critical load refers to a load to which power is supplied from the vehiclevia the EVSEand the critical load distribution boardin a state where power supply from the gridis stopped, such as during a power failure. The load electrically connected to the critical load distribution boardis capable of operating using AC power supplied from the critical load distribution board.illustrate theV critical loadand theV critical loadas examples of at least one critical load. TheV critical loadis an electric power device that operates using single-phaseV AC power from the critical load distribution board. TheV critical loadis an electric power device that operates using single-phaseV AC power from the critical load distribution board. In one example, the AC power from the critical load distribution boardcan be supplied to each critical load in a residence (consumer) via an outlet within the residence. In this example, the critical load distribution boardis an example of a second distribution board.

62 61 4 62 9 4 a a Moreover, the critical load distribution boardis capable of switching the AC power supplied to the critical load between the AC power from the distribution boardand the AC power from the EVSE. This switching is performed, for example, by user operation, but may also be performed automatically in a case where the critical load distribution boarddetects a power failure of the grid, or in response to a control signal from the EVSE, or in response to a control signal from a home energy management system (HEMS) that controls, monitors, and manages each of the consumer's power facilities and power devices.

211 21 41 4 211 41 211 41 a Moreover, each the control unitof the bidirectional chargerand the control unitof the EVSEincludes, for example, at least one processor (not illustrated) and at least one memory (not illustrated), and has a hardware configuration using a conventional computer. Each of the control unitsandcan be implemented using, for example, a digital signal processor (DSP). Alternatively, each of the control unitsandmay implement respective functions by, for example, a processor such as a central processing unit (CPU) executing a computer program stored in an auxiliary storage device such as a read-only memory (ROM), the program being loaded into a main storage device such as a random-access memory (RAM), or may implement the respective functions by dedicated hardware circuits (such as semiconductor integrated circuits).

211 2 211 2 4 2 2 2 a Moreover, the control unitmay also be implemented by, for example, an electronic control unit (ECU) provided inside the vehicle, a domain control unit (DCU) such as a cockpit domain controller (CDC) that integrates a plurality of ECUs, or an on-board unit (OBU), all of which are computers. In addition, the control unitmay also transmit and receive information to and from other ECUs installed in the vehicleor external devices (e.g., the EVSE) connected to the vehiclevia an in-vehicle network, such as a controller area network (CAN), Ethernet (registered trademark), or universal serial bus (USB; registered trademark) within the vehicle, or may communicate with information processing devices external to the vehiclevia a network such as the Internet.

1 Next, an exemplary operation of the power systemconfigured as described above will be described.

3 FIG. 4 FIG. 1 2 1 a is a flowchart illustrating an exemplary operation of the power systemaccording to the first embodiment in the islanded operation.is a diagram illustrating an example of the connection state in the islanded operation in a case where the first vehicleis connected to the power systemaccording to the first embodiment.

3 FIG. 2 101 9 2 101 102 In the procedure illustrated in, if charging and discharging of the vehicleis not stopped due to a power failure or the like (S: No), the system waits in a standby state. On the other hand, if the power supply from the gridis stopped due to a power failure or the like, charging and discharging of the vehicleis stopped (S: Yes), and then the process proceeds to step S.

41 4 9 1 2 40 41 4 9 211 2 9 1 2 212 2 4 2 4 a a a a a Moreover, the control unitof the EVSEmay detect whether the power supply from the gridis stopped due to a power failure or the like based on a measurement result of a voltage sensor that is provided to be capable of measuring the potential difference between a pair of power lines Land L(a pair of voltage lines) at the grid-side input/output end. Alternatively, the control unitof the EVSEmay detect whether the power supply from the gridis stopped due to a power failure or the like based on a notification (control signal) from the HEMS. Alternatively, the control unitof the vehiclemay detect whether the power supply from the gridis stopped due to a power failure or the like based on a measurement result of a voltage sensor that is provided to be capable of measuring a potential difference between the pair of power lines Land Lof the power conversion unit. Moreover, whether charging and discharging of the vehicleis stopped may be determined based on an input result to the EVSEor HEMS by a user, or based on a notification (control signal) from the vehicleto the EVSEor the HEMS.

3 FIG. 4 FIG. 2 62 102 101 2 62 102 103 In the procedure illustrated in, if charging and discharging of the vehicleis stopped due to a power failure or the like and the critical load distribution boardis not switched to the critical load side (S: No), the process returns to step S. On the other hand, as illustrated in, if charging and discharging of the vehicleis stopped due to a power failure or the like and the critical load distribution boardis switched to the critical load side (S: Yes), the process proceeds to step S.

41 4 62 4 62 4 a a a Moreover, the control unitof the EVSEmay determine whether the critical load distribution boardis switched to the critical load side based on the user's input to the EVSEor the HEMS, or based on a notification (control signal) from the critical load distribution boardor the HEMS to the EVSE.

3 FIG. 2 62 103 101 2 62 103 104 In the procedure of, if charging and discharging of the vehicleis stopped due to a power failure or the like, the critical load distribution boardis switched to the critical load side, and the initiation of the islanded operation is not instructed (S: No), the process returns to step S. On the other hand, if charging and discharging of the vehicleis stopped due to a power failure or the like, the critical load distribution boardis switched to the critical load side, and the initiation of the islanded operation is instructed (S: Yes), the process proceeds to step S.

41 4 4 4 62 62 41 4 a a a a Moreover, the control unitof the EVSEmay determine whether an instruction to initiate the islanded operation is issued based on the user's input to the EVSEor the HEMS, or based on a notification (control signal) sent to the EVSEfrom the critical load distribution boardor the HEMS. Moreover, in a configuration in which the critical load distribution boardautomatically switches to the critical load side upon detection of a power failure, the control unitof the EVSEmay determine that an instruction to initiate the islanded operation is issued upon detection of a power failure or the like.

41 4 213 2 49 104 a In a case where the islanded operation is to be initiated, the control unitof the EVSEchecks whether the neutral point connection switchis present in the vehicleconnected via the charge/discharge cable(S).

41 4 213 213 2 41 4 213 2 2 2 213 41 4 213 4 213 49 a a a a Moreover, the control unitof the EVSEmay determine the presence or absence of the neutral point connection switchbased on information (control signal) indicating the presence or absence of the neutral point connection switchreceived from the vehiclevia the control pilot line CP. Alternatively, the control unitof the EVSEmay determine the presence or absence of the neutral point connection switchbased on information (control signal) indicating the type of the vehiclereceived from the vehiclevia the control pilot line CP and information indicating the correspondence between the type of the vehicleand the presence or absence of the neutral point connection switch, the correspondence being stored in an internal memory in advance. Alternatively, the control unitof the EVSEmay determine the presence or absence of the neutral point connection switchbased on a result of input (or pre-registration result) made by the user to the EVSEor the HEMS. Moreover, the presence or absence of the neutral point connection switchmay be checked in advance, for example, at the time of connection of the charge/discharge cable, and the check result may be stored in the internal memory.

4 FIG. 2 213 105 41 4 42 4 101 43 106 41 4 211 21 2 200 107 a a a a a As illustrated in, in the case of the first vehicleequipped with the neutral point connection switch(S: Yes), the control unitof the EVSEconfirms that the grid-side relayof the EVSEis in the off state (because the relay is turned off in a case where a power failure is detected, i.e., at the time of S: Yes), and turns on the islanded-side relay(S). Then, the control unitof the EVSEtransmits a control signal to the control unitof the bidirectional chargerof the first vehicleto instruct discharge at single-phaseV (first voltage), i.e., a control signal instructing the islanded operation (S).

211 2 4 213 108 212 200 4 109 a a a 3 FIG. The control unitof the first vehicle, which receives the control signal instructing the islanded operation from the EVSE, turns on the neutral point connection switch(S), controls the power conversion of the power conversion unitto generate single-phaseV (first voltage), and initiates the islanded operation to supply power to the EVSE(S). Then, the procedure inends.

2 2 213 2 105 2 213 41 4 a b b a 3 FIG. On the other hand, if the vehicleis not the first vehicleequipped with the neutral point connection switch, i.e., the second vehicle(S: No), the procedure inends. In other words, if the second vehicle, which is not equipped with the neutral point connection switch, is connected, the control unitof the EVSEdoes not allow the islanded operation and stops the processing for islanded operation.

41 4 4 9 41 4 211 2 211 2 212 213 41 4 43 4 42 62 62 41 4 211 2 41 4 62 a a a a a a a 1 2 FIGS.and Moreover, the control unitof the EVSEmay also determine the end of the islanded operation based on a result of user input to the EVSEor HEMS or detection of power supply from the grid(restoration from a power failure). At the end of the islanded operation, the control unitof the EVSEtransmits a control signal instructing the end of the islanded operation to the control unitof the vehicle. In addition, upon receiving the transmitted control signal, the control unitof the vehiclestops operation of the power conversion unitand turns off the neutral point connection switch. Thereafter, the control unitof the EVSEturns off the islanded-side relayof the EVSEand turns on the grid-side relay. Then, the critical load distribution boardis switched to the normal load side (see). Moreover, the switching of the critical load distribution boardmay be performed before the control signal instructing the end of the islanded operation is transmitted from the control unitof the EVSEto the control unitof the vehicle. The control unitof the EVSEmay also determine the end of the islanded operation based on the switching of the critical load distribution board.

1 2 2 213 213 200 212 49 a a As described above, the power systemaccording to the present embodiment enables the islanded operation by the vehiclein a case where the first vehicleequipped with the neutral point connection switchis connected. In the islanded operation, the neutral point connection switchis turned on to establish electrical conduction between the neutral point NP of the AC-side input/output endof the power conversion unitand the protective earth line PE of the charge/discharge cable, which is functionally grounded to the chassis potential.

2 200 2 4 200 200 100 212 21 2 212 4 21 200 a a Conventionally, a charging connector of the vehiclefor single-phaseV does not have an N-phase terminal, and thus in the islanded operation by the vehicleconnected to a consumer such as a residence via the EVSEfor single-phaseV, both a single-phaseV device and a single-phaseV device could not be made available. Additionally, if the neutral point NP of the power conversion unitof the on-board bidirectional chargeris configured to be connected to the chassis potential of the vehicle, the neutral point NP of the power conversion unitand the N phase of the single-phase three-wire system on the EVSEside can be set to the same potential, but such a configuration posed a problem in that the on-board bidirectional chargerwould violate standards during single-phaseV charging.

200 1 2 200 212 2 4 200 100 212 a a In this situation, the above-described configuration according to the present embodiment enables single-phaseV (first voltage) AC power to be generated between the pair of power lines Land Lof the AC-side input/output endof the power conversion unitof the vehicle, with the chassis potential as a reference. In the EVSEto which the relevant AC power is supplied, it is possible to extract both single-phaseV (first voltage) AC power and single-phaseV (second voltage) AC power, with the potential of the protective earth line PE electrically connected to the neutral point NP of the power conversion unitas a reference.

1 1 100 200 200 213 1 2 212 Thus, the power systemaccording to the present embodiment enables the neutral line potential at a consumer receiving power supply from a single-phase three-wire power grid to be appropriately determined for power supply from the on-board charger to the consumer. In other words, the power systemaccording to the present embodiment enables the use of both single-phaseV andV devices in the islanded operation of a vehicle. In other modes including single-phaseV charging, since the neutral point connection switchis turned off, neither the power lines Land Lnor the neutral line NP of the power conversion unitare functionally grounded to the chassis potential, thereby achieving a configuration that complies with standards.

The following describes modifications and other embodiments of the present disclosure. Note that the following descriptions of modifications and embodiments will mainly focus on differences, and redundant description overlapping with the foregoing description will be omitted as appropriate.

5 FIG. 5 FIG. 1 2 1 a is a diagram illustrating an exemplary configuration of a power systemaccording to a modification of the first embodiment.exemplifies a connection state during the islanded operation in a case where a first vehicleis connected to the power systemaccording to the present modification.

5 FIG. 1 21 2 214 a As illustrated in, in the power systemaccording to the present modification, a bidirectional chargerof the first vehiclefurther includes a current sensor.

21 214 214 213 214 In the bidirectional charger, the current sensoris provided in series with the functional grounding line FG at a chassis potential. In other words, the current sensoris provided between the functional grounding line FG at the chassis potential and the side of the protective earth line PE of the neutral point connection switch. In other words, the current sensordetects current (insulation failure) flowing through the functional grounding line FG at the chassis potential.

21 211 213 214 211 212 213 In the bidirectional charger, the control unitdetermines that the islanded operation is to be stopped in a case where, with the neutral point connection switchturned on, the current sensordetects a current equal to or greater than a predetermined threshold value stored in an internal memory. If the islanded operation is determined to be stopped, the control unitstops power conversion by the power conversion unitand also turns off the neutral point connection switch.

1 21 2 214 213 2 a a As described above, in the power systemaccording to the present modification, the bidirectional chargerof the first vehicleis provided with the current sensorconfigured to detect insulation failure between the neutral point connection switchand the functional grounding line FG at the chassis potential. This configuration enables insulation failure detection and improves safety in the islanded operation by the first vehicle.

6 FIG. 6 FIG. 1 2 1 a is a diagram illustrating an exemplary configuration of a power systemaccording to a second embodiment.illustrates an example of the connection state during the islanded operation in a case where a first vehicleis connected to the power systemaccording to the second embodiment.

4 200 100 213 4 213 4 4 b b b An EVSEaccording to the second embodiment is a power supply apparatus which, in a case where the islanded operation is determined to be performed, switches the connection with the consumer side between a single-phase three-wireV system and a single-phaseV system depending on the presence or absence of a neutral point connection switch. In other words, the EVSEaccording to the second embodiment is a power supply apparatus that instructs an output voltage value depending on the presence or absence of the neutral point connection switch. The EVSEaccording to the second embodiment is an example of the EVSEaccording to the present disclosure.

6 FIG. 4 44 b As illustrated in, the EVSEaccording to the present embodiment further includes an LN short-circuit switch.

44 40 43 43 40 44 40 43 44 1 2 49 1 2 40 40 43 c b c c c 6 FIG. The LN short-circuit switchis provided between an islanded-side output endand an islanded-side relay, or between the islanded-side relayand a vehicle-side input/output end.illustrates an example of the LN short-circuit switchprovided between the output end for islanded operationand the islanded-side relay. The LN short-circuit switchis a short-circuit switch that electrically connects one of a pair of power lines Land Lof a charge/discharge cableto either one of a pair of power lines Land L(pair of voltage lines) of the corresponding islanded-side output end, or to a neutral line N of the output end for islanded operation, via the islanded-side relay.

6 FIG. 44 2 49 2 40 43 c The example inillustrates the LN short-circuit switchthat electrically connects the power line Lof the charge/discharge cableto either the power line L(voltage line) of the output end for islanded operationor to the neutral line N, via the islanded-side relay.

4 41 42 43 44 41 42 43 44 41 4 b b The EVSEincludes a control unitelectrically connected to a grid-side relay, the islanded-side relay, and the LN short-circuit switchvia a control line. The control unitcontrols the operation of the grid-side relay, the islanded-side relay, and the LN short-circuit switch. In this example, the control unitof the EVSEis an example of a second control unit.

41 4 2 49 41 42 61 49 41 200 9 61 2 49 2 2 2 1 2 20 21 200 b a b a In one example, the control unitof the EVSEcontrols grid-connected supply operation. In the grid-connected supply operation, in a case where the vehicleis connected via the charge/discharge cable, the control unitturns on the grid-side relayto establish electrical conduction between the distribution boardand the charge/discharge cable. Further, in this state, the control unitsupplies single-phaseV (first voltage) AC power supplied from the gridvia the distribution boardto the vehicleconnected via the charge/discharge cable. In other words, in the grid-connected supply operation, for each of the vehicles, i.e., the first vehicleand a second vehicle, the potential difference between the pair of power lines Land Lof an AC-side input/output endof a bidirectional chargeris single-phaseV (first voltage).

41 4 2 49 41 42 61 49 41 200 2 49 61 2 2 2 1 2 20 21 200 b a b a In one example, the control unitof the EVSEcontrols grid-interconnection operation. In the grid-interconnection operation, in a case where the vehicleis connected via the charge/discharge cable, the control unitturns on the grid-side relayto establish electrical conduction between the distribution boardand the charge/discharge cable. In this state, the control unitsupplies single-phaseV (first voltage) AC power supplied from the vehiclevia the charge/discharge cableto the distribution board. In other words, in the grid-interconnection operation, for each of the vehicles, i.e., the first vehicleand the second vehicle, the potential difference between the pair of power lines Land Lof the AC-side input/output endsof the bidirectional chargeris single-phaseV (first voltage).

9 41 4 2 b In one example, in a case where a power failure of the gridis detected, the control unitof the EVSEcontrols the islanded operation of the vehicle.

9 41 4 213 2 49 b In one example, in the islanded operation, if a power failure of the gridis detected, the control unitof the EVSEchecks the presence or absence of the neutral point connection switchin the vehicleconnected via the charge/discharge cable.

41 43 62 49 41 211 21 2 49 41 213 2 49 62 In one example, in the islanded operation, the control unitturns on the islanded-side relayto establish electrical conduction between a critical load distribution boardand the charge/discharge cable. Further, in this state, the control unitoutputs a control signal instructing the islanded operation to the control unitof the bidirectional chargerprovided in the vehicleconnected via the charge/discharge cable. Then, the control unitsupplies AC power, the voltage of which depends on the presence or absence of the neutral point connection switchand which is supplied from the vehiclevia the charge/discharge cable, to the critical load distribution board.

213 In one example, the control signal instructing the islanded operation specifies an output voltage value depending on the presence or absence of the neutral point connection switch.

2 49 2 213 200 200 1 2 40 1 2 20 21 2 200 1 2 20 21 2 100 a a a a a a If the vehicleconnected via the charge/discharge cableis the first vehicleand has a neutral point connection switch, the control signal specifies single-phaseV (first voltage) as the output voltage value. The single-phaseV (first voltage) mentioned above is the potential difference between the pair of power lines Land L(pair of voltage lines) at the grid-side input/output endsin the grid-connected supply operation or the grid-interconnection operation. In other words, in the islanded operation, the potential difference between the pair of power lines Land Lof the AC-side input/output endsof the bidirectional chargerof the first vehicleis single-phaseV (first voltage). In the islanded operation, the potential difference between each of the pair of power lines Land Lof the AC-side input/output endsof the bidirectional chargerof the first vehicleand a neutral point NP is single-phaseV (second voltage).

2 49 2 213 100 100 1 2 40 1 2 20 21 2 100 b a a b If the vehicleconnected via the charge/discharge cableis the second vehicleand does not have the neutral point connection switch, the control signal specifies single-phaseV (second voltage) as the output voltage. The single-phaseV (second voltage) is the potential difference between the neutral line N and each of the pair of power lines Land L(pair of voltage lines) at the grid-side input/output endin the grid-connected supply operation or the grid-interconnection operation. In other words, in the islanded operation, the potential difference between the pair of power lines Land Lof the AC-side input/output endof the bidirectional chargerof the second vehicleis single-phaseV (second voltage).

41 4 44 2 49 2 213 41 1 2 49 1 2 40 1 2 b a c In one example, in the islanded operation, the control unitof the EVSEturns off the LN short-circuit switchin a case where the vehicleconnected via the charge/discharge cableis the first vehicleand has the neutral point connection switch. Then, the control unitoutputs a control signal instructing the islanded operation in a state that one line of the pair of power lines Land Lof the charge/discharge cableis electrically connected to a corresponding one line of the pair of power lines Land L(pair of voltage lines) of the output end for islanded operation, i.e., in a state that the power lines Lare electrically connected to each other or the power lines Lare electrically connected to each other.

41 4 44 2 49 2 213 41 1 2 49 40 b b c In one example, in the islanded operation, the control unitof the EVSEturns on the LN short-circuit switchin a case where the vehicleconnected via the charge/discharge cableis the second vehiclethat does not have a neutral point connection switch. Then, the control unitoutputs a control signal instructing the islanded operation in a state that one line of the pair of power lines Land Lof the charge/discharge cableis electrically connected to the neutral line N of the output end for islanded operation.

7 FIG. 8 FIG. 1 2 1 b is a flowchart illustrating an exemplary operation of the power systemaccording to the second embodiment in the islanded operation.is a diagram illustrating an example of the connection state in the islanded operation in a case where the second vehicleis connected to the power systemaccording to the second embodiment.

2 213 105 41 4 44 2 201 42 43 106 107 109 a b 6 FIG. 6 FIG. 3 FIG. In the case of the first vehicleequipped with the neutral point connection switch(S: Yes), as illustrated in, the control unitof the EVSEturns off the LN short-circuit switchto connect the corresponding power line (power line Lin) (S), confirms that the grid-side relayis in an off state, and turns on the islanded-side relay(S). Steps Sto Sare similar to those in, so their descriptions are omitted herein.

2 2 213 2 105 41 4 44 2 202 42 43 203 41 4 100 211 21 2 204 a b b b b 8 FIG. 8 FIG. On the other hand, if the connected vehicleis not the first vehicleequipped with the neutral point connection switch, i.e., in the case of the second vehicle(S: No), the control unitof the EVSEturns on the LN short-circuit switchto short-circuit one of the power lines (power line Lin) to the neutral line N (S), as illustrated in, confirms that the grid-side relayis in an off state, and turns on the islanded-side relay(S). Then, the control unitof the EVSEtransmits a control signal instructing discharge at single-phaseV (second voltage), namely a control signal instructing the islanded operation, to the control unitof the bidirectional chargerof the second vehicle(S).

211 2 4 2 212 100 4 205 b b b b 7 FIG. The control unitof the second vehicle, upon receiving a control signal from the EVSEinstructing the second vehicleto perform the islanded operation, controls the power conversion of the power conversion unitto generate single-phaseV (second voltage) and supplies the generated power to the EVSE, thereby initiating the islanded operation (S). Then, the procedure ofends.

4 2 213 2 213 4 2 200 2 44 2 213 4 2 100 2 b a b b b In this way, in the islanded operation, the EVSEaccording to the second embodiment instructs the vehicleto operate at an output voltage value that depends on whether the neutral point connection switchis present or absent. Specifically, in a case where the first vehicleequipped with the neutral point connection switchis connected, the EVSEinstructs the vehicleto operate at an output voltage value of single-phaseV with the power line Land the neutral line N not being short-circuited by the LN short-circuit switch, and in a case where the second vehiclenot equipped with a neutral point connection switchis connected, the EVSEinstructs the vehicleto operate at an output voltage value of single-phaseV with the power line Land the neutral line N being short-circuited.

4 200 1 2 9 21 4 200 100 4 21 100 4 100 21 100 7 62 200 100 b b b b c With this configuration, in the EVSEconnected to the single-phase three-wireV (Land L) of the gridand in the on-board bidirectional charger, when the islanded operation is determined to be performed, the EVSEswitches the connection with the consumer side from the single-phase three-wireV system to the single-phaseV system. Then, the EVSEissues a command to the bidirectional chargerto operate the islanded operation at single-phaseV. In addition, the EVSEsupplies the single-phaseV output from the bidirectional chargerupon receiving the command to aV critical loadconnected to the critical load distribution board. In other words, this configuration enables both single-phaseV charging (grid-connected supply operation) and islanded operation, which allows the use of at leastV devices.

9 FIG. 9 FIG. 1 2 1 b is a diagram illustrating an exemplary configuration of a power systemaccording to a third embodiment.illustrates an example of a connection state in the islanded operation in a case where a second vehicleis connected to the power systemaccording to the third embodiment.

4 213 200 100 4 4 c c An EVSEaccording to the third embodiment is a power supply apparatus that, irrespective of the presence or absence of the neutral point connection switch, switches the connection with the consumer side from a single-phase three-wireV system for grid-connected supply operation or grid-interconnection operation to a single-phaseV system for islanded operation in a case where the islanded operation is determined to be performed. The EVSEaccording to the third embodiment is an example of the EVSEaccording to the present disclosure.

9 FIG. 1 63 62 63 As illustrated in, the power systemaccording to the present embodiment includes an islanded outletinstead of the critical load distribution board. In this example, the islanded outletis an example of the second distribution board.

63 4 62 63 61 63 63 100 7 200 7 63 4 100 7 c c d c c The islanded outletis electrically connected to the EVSEbut, unlike the critical load distribution board, the islanded outletis not connected to a distribution board. The islanded outletis capable of being electrically connected with at least one critical load. Moreover, the critical load connected to the islanded outletincludes aV critical load, but not aV critical load. In other words, the islanded outletsupplies AC power from the EVSEto theV critical load.

4 43 40 4 40 43 63 49 43 63 49 43 1 40 1 40 43 40 2 40 c c c b c b c b In the EVSE, an islanded-side relayis provided between an output endfor islanded operation of the EVSEand a vehicle-side input/output end. In other words, the islanded-side relayis provided between the islanded outletand a charge/discharge cable. The islanded-side relayswitches between conduction and disconnection between the islanded outletand the charge/discharge cable. Specifically, the islanded-side relayswitches between conduction and disconnection between the power line L(voltage line) of the output endfor islanded operation and the power line Lof the vehicle-side input/output end. Additionally, the islanded-side relayswitches between conduction and disconnection between a neutral line N of the output endfor islanded operation and a power line Lof the vehicle-side input/output end.

4 1 2 2 1 2 9 4 1 2 2 1 2 100 7 4 200 100 c c c c Thus, in the grid-connected supply operation or the grid-interconnection operation, the EVSEaccording to the present embodiment electrically connects a pair of power lines Land Lon the vehicleside to a pair of power lines Land L(pair of voltage lines) on the gridside. Additionally, in the islanded operation, the EVSEelectrically connects one line of the pair of power lines Land Lon the vehicleside to one of the corresponding pair of power lines Land L(pair of voltage lines) on theV critical loadside, and electrically connects the other to the neutral line N. This configuration enables the EVSEaccording to the present embodiment to establish electrical connection with the consumer side via a single-phase three-wireV system during the grid-connected supply operation or the grid-interconnection operation, and via a single-phaseV system during the islanded operation.

10 FIG. 1 is a flowchart illustrating an exemplary operation of the power systemaccording to the third embodiment in the islanded operation.

9 2 101 103 If the power supply from the gridis stopped due to a power failure or other reason, charging and discharging of the vehicleare stopped (S: Yes), and then the process proceeds to step S.

10 FIG. 2 103 101 2 103 203 In the procedure in, in a case where the charging and discharging of the vehicleare stopped due to a power failure or the like and an instruction to initiate the islanded operation is not issued (S: No), the process returns to step S. On the other hand, if charging and discharging of the vehicleare stopped due to a power failure or the like and an instruction to initiate the islanded operation is issued (S: Yes), the process proceeds to step S.

41 4 42 43 203 41 4 100 211 21 2 2 49 301 c c a b 9 FIG. In a case where the islanded operation is to be initiated, the control unitof the EVSE, as illustrated in, confirms that the grid-side relayis in an off state and turns on the islanded-side relay(S). Then, the control unitof the EVSEtransmits a control signal instructing discharge at single-phaseV (second voltage), i.e., a control signal instructing the islanded operation, to the control unitof the bidirectional chargerof the first vehicleor the second vehicleconnected via the charge/discharge cable(S).

211 2 2 4 212 100 100 4 302 a b c c 10 FIG. The control unitof the first vehicleor the second vehicle, upon receiving the control signal instructing the islanded operation from the EVSE, controls the power conversion of the power conversion unitto generate single-phaseV (second voltage), and initiates the islanded operation by supplying the single-phaseV to the EVSE(S). Then, the procedure ofends.

4 213 200 100 c In this way, the EVSEaccording to the third embodiment, irrespective of the presence or absence of the neutral point connection switch, switches the connection with the consumer side from the single-phase three-wireV system for the grid-connected supply operation or the grid-interconnection operation to the single-phaseV system for the islanded operation in a case where it determines that the islanded operation is to be performed.

200 100 This configuration enables both the single-phaseV charging (grid-connected supply operation) and the islanded operation in which aV device is usable.

Moreover, in the present disclosure, the expression "whether or not A" shall encompass at least any one of a determination that "A" holds and a determination that "A" does not hold. In other words, in each of the embodiments described above, the determination of "whether or not A" may be implemented by determining that "A" holds, by determining that "A" does not hold, or by both.

1 Computer programs executed by each device in the power systemaccording to the present disclosure may also be provided by being recorded, in an installable file format or in an executable file format, on a non-transitory computer-readable recording medium such as a CD-ROM, FD, CD-R, or DVD, and provided.

1 1 Further, the programs executed by each device of the power systemaccording to the present disclosure may also be provided by being stored on a computer connected to a network such as the Internet and downloaded via the network. Alternatively, the programs executed by each device of the power systemaccording to the present disclosure may be provided or distributed via a network such as the Internet.

1 The programs executed by each device of the power systemaccording to the present disclosure may also be provided by being pre-installed in ROM or the like.

According to at least one of the embodiments described above, it is possible for a consumer receiving power supply from a single-phase three-wire power grid to utilize an on-board battery as a power source.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.

According to the foregoing description, the following technologies of the present disclosure are provided.

(A1)

A power conversion device including, a power conversion unit having an AC-side input/output end that is electrically connected to a charge/discharge socket to which a charge/discharge cable is detachably connected and that inputs and outputs AC power and a DC-side input/output end that inputs and outputs DC power, and configured to convert AC and DC power between power inputted from either the AC-side or the DC-side input/output end and output the converted power from the other of the AC-side or the DC-side input/output end;

a neutral point connection switch provided between a neutral point of a pair of power lines of the AC-side input/output end and a functional grounding line at a chassis potential electrically connected to a protective earth line of the charge/discharge cable connected to the charge/discharge socket; and

a first control unit configured to control operations of the power conversion unit and the neutral point connection switch,

wherein the first control unit controls an islanded operation in which, in a state where the neutral point connection switch is turned on to establish conduction between the neutral point of the AC-side input/output end and the functional grounding line at the chassis potential, DC power input from the DC-side input/output end is converted into AC power by the power conversion unit and output from the AC-side input/output end.

(A2)

The power conversion device according to (A1), wherein

the AC power output from the AC-side input/output end in the islanded operation includes a first voltage that is a potential difference between the pair of power lines of the AC-side input/output end and a second voltage that is a potential difference between each of the pair of power lines of the AC-side input/output end and the neutral point, and

an amplitude of the first voltage is twice an amplitude of the second voltage.

(A3)

The power conversion device according to (A1) or (A2), wherein the first control unit further controls a grid-connected supply operation in which, in a state where the neutral point connection switch is turned off to disconnect between the neutral point of the AC-side input/output end and the functional grounding line at the chassis potential, AC power input from the AC-side input/output end is converted into DC power by the power conversion unit and output from the DC-side input/output end.

(A4)

The power conversion device according to any one of (A1) to (A3), wherein the first control unit further controls a grid-interconnection operation in which, in a state where the neutral point connection switch is turned off to disconnect between the neutral point of the AC-side input/output end and the functional grounding line at the chassis potential, DC power input from the DC-side input/output end is converted into AC power by the power conversion unit and output from the AC-side input/output end.

(A5)

The power conversion device according to any one of (A1) to (A4),

further including a current sensor provided in series with the functional grounding line at the chassis potential,

wherein the first control unit, in a case where a current equal to or greater than a predetermined threshold is detected by the current sensor in a state where the neutral point connection switch is turned on, stops the islanded operation.

(A6)

A vehicle including

the power conversion device according to any one of (A1) to (A5);

a battery electrically connected to the DC-side input/output end; and

the charge/discharge socket,

wherein the charge/discharge socket has

a pair of power terminals electrically connected to a pair of power lines of the charge/discharge cable,

a protective earth terminal electrically connected to the protective earth line of the charge/discharge cable, and

a control terminal electrically connected to a control line of the charge/discharge cable,

the pair of power terminals of the charge/discharge socket are electrically connected to the pair of power lines of the AC-side input/output end of the power conversion device,

the protective earth terminal of the charge/discharge socket is electrically connected to the functional grounding line at the chassis potential,

the control terminal of the charge/discharge socket is electrically connected to the first control unit of the power conversion device and inputs a control signal from outside via the charge/discharge cable.

(A7)

The vehicle according to (A6), wherein

the first control unit of the power conversion device turns on the neutral point connection switch in a case where the islanded operation is instructed by the control signal from outside.

(A8)

A power system including,

a first vehicle being the vehicle according to (A6);

a power supply apparatus electrically connected to the vehicle via the charge/discharge cable;

a first distribution board provided between the power grid and the power supply apparatus; and

a second distribution board provided between the first distribution board and the power supply apparatus,

wherein the power supply apparatus includes

a grid-side switch provided between the first distribution board and the charge/discharge cable,

an islanded-side switch provided between the second distribution board and the charge/discharge cable, and

a second control unit configured to control operations of the grid-side switch and the islanded-side switch,

the second control unit,

in a case where the first vehicle is connected via the charge/discharge cable, controls a grid-connected supply operation in which, in a state where the grid-side switch is turned on to establish conduction between the first distribution board and the charge/discharge cable, AC power supplied from the power grid via the first distribution board is supplied to the first vehicle connected via the charge/discharge cable, or a grid-interconnection operation in which AC power supplied from the first vehicle via the charge/discharge cable is supplied to the first distribution board,

the second control unit, in a case where a power failure of the power grid is detected, controls an islanded operation in which, in a state where the islanded-side switch is turned on to establish conduction between the second distribution board and the charge/discharge cable, a control signal instructing the islanded operation is output to the first control unit of the power conversion device provided in the first vehicle connected via the charge/discharge cable, and AC power supplied from the first vehicle via the charge/discharge cable is supplied to the second distribution board.

(A9)

The power system according to (A8), wherein the first control unit of the power conversion device in the first vehicle turns on the neutral point connection switch in a case where the islanded operation is instructed by the control signal from outside.

(A10)

The power system according to (A8) or (A9), wherein, in a case where a second vehicle in which the power conversion device without the neutral point connection switch is provided is connected via the charge/discharge cable, the second control unit controls a grid-connected supply operation in which, in a state where the grid-side switch is turned on to establish conduction between the first distribution board and the charge/discharge cable, AC power supplied from the power grid via the first distribution board is supplied to the second vehicle connected via the charge/discharge cable, or a grid-interconnection operation in which AC power supplied from the second vehicle via the charge/discharge cable is supplied to the first distribution board.

(A11)

The power system according to any one of (A8) to (A10), wherein, in a case where a power failure of the power grid is detected, the second control unit checks whether the neutral point connection switch is present in the vehicle to which the charge/discharge cable is connected, and in a case where the neutral point connection switch is not present, does not output the control signal instructing the islanded operation.

(B1)

A power supply apparatus comprising:

a charge/discharge cable to which a vehicle is connected, the charge/discharge cable including a pair of power lines, a protective earth line at ground potential, and a control line;

a grid-side switch provided between a grid-side input/output end and the charge/discharge cable, the grid-side input/output end being electrically connected to a power grid via a first distribution board;

an islanded-side switch provided between an output end for islanded operation and the charge/discharge cable, the output end for islanded operation being electrically connected to a second distribution board different from the first distribution board; and

a second control circuit configured to

control operations of the grid-side switch and the islanded-side switch, and

communicate, via the control line, with a first control circuit of a power conversion device provided in the vehicle, wherein

a pair of voltage lines of the grid-side input/output end is electrically connected to a pair of power lines of the charge/discharge cable via the grid-side switch,

a pair of voltage lines of the output end for islanded operation is electrically connected to the pair of power lines of the charge/discharge cable via the islanded-side switch,

the pair of power lines of the charge/discharge cable is electrically connected to a pair of power lines of an AC-side input/output end of the power conversion device in the vehicle, the AC-side input/output end serving to input and output AC power,

a neutral line of the grid-side input/output end and the protective earth line of the charge/discharge cable are connected to ground potential,

the second control circuit is configured to, when the vehicle is connected via the charge/discharge cable,

establish conduction between the first distribution board and the charge/discharge cable by turning on the grid-side switch, and

control a grid-connected supply operation or a grid-interconnection operation while keeping the conduction between the first distribution board and the charge/discharge cable, the grid-connected supply operation being operation in which AC power at a first voltage supplied from the power grid via the first distribution board is supplied to the vehicle, the grid-interconnection operation being operation in which AC power at the first voltage supplied from the vehicle via the charge/discharge cable is supplied to the first distribution board,

the second control circuit is configured to, when a power failure of the power grid is detected,

establish conduction between the second distribution board and the charge/discharge cable by turning on the islanded-side switch,

output a control signal instructing the islanded operation to the first control circuit of the power conversion device while keeping the conduction between the second distribution board and the charge/discharge cable, and

control islanded operation in which AC power supplied from the vehicle via the charge/discharge cable is supplied to the second distribution board, and

the control signal instructing the islanded operation specifies, as an output voltage value, a second voltage that is a potential difference between each line of the pair of voltage lines of the grid-side input/output end and the neutral line of the grid-side input/output end in the grid-connected supply operation or the grid-interconnection operation.

(B2)

The power supply apparatus according to (B1), wherein

a neutral line of the output end for islanded operation is electrically connected to the protective earth line of the charge/discharge cable via the islanded-side switch,

the protective earth line of the charge/discharge cable is electrically connected to a functional grounding line at a chassis potential in the power conversion device of the vehicle,

the second control circuit is configured to check whether a neutral point connection switch is provided between a neutral point of the pair of power lines of the AC-side input/output end of the power conversion device of the vehicle and the functional grounding line at chassis potential, and

the control signal instructing the islanded operation is configured to, when the vehicle is a first vehicle with the neutral point connection switch, specify the first voltage as an output voltage value, the first voltage being a potential difference between the pair of voltage lines of the grid-side input/output end in the grid-connected supply operation or the grid-interconnection operation, and

the control signal instructing the islanded operation is further configured to specify the second voltage as the output voltage value when the vehicle is a second vehicle without the neutral point connection switch.

(B3)

The power supply apparatus according to (B2), further comprising a short-circuit switch provided between the output end for islanded operation and the islanded-side switch or between the islanded-side switch and a vehicle-side input/output end, the short-circuit switch being configured to electrically connect one line of the pair of power lines of the charge/discharge cable to the corresponding one line of the pair of voltage lines of the output end for islanded operation or to the neutral line of the output end for islanded operation via the islanded-side switch, wherein

the second control circuit is configured to, when the first vehicle is connected via the charge/discharge cable, output the control signal instructing the islanded operation in a state that the short-circuit switch is turned off to electrically connect one line of the pair of power lines of the charge/discharge cable to the corresponding one line of the pair of voltage lines of the output end for islanded operation, and

the second control circuit is configured to, when the second vehicle is connected via the charge/discharge cable, output the control signal instructing the islanded operation in a state that the short-circuit switch is turned on to electrically connect one line of the pair of power lines of the charge/discharge cable to the neutral line of the output end for islanded operation.

(B4)

A power system comprising:

the power supply apparatus according to (B2) or (B3);

the vehicle electrically connected to the power supply apparatus via the charge/discharge cable;

the first distribution board provided between the power grid and the power supply apparatus; and

the second distribution board provided between the first distribution board and the power supply apparatus, wherein,

in the grid-connected supply operation or the grid-interconnection operation, a potential difference between the pair of power lines of the AC-side input/output end of the power conversion device of the vehicle is the first voltage,

in the islanded operation, a potential difference between the pair of power lines of the AC-side input/output end of the power conversion device of the first vehicle is the first voltage,

in the islanded operation, a potential difference between each of the pair of power lines of the AC-side input/output end of the power conversion device of the first vehicle and a neutral point of the pair of power lines of the AC-side input/output end is the second voltage, and

in the islanded operation, a potential difference between the pair of power lines of the AC-side input/output end of the power conversion device of the second vehicle is the second voltage.

(B5)

The power system according to (B4), wherein

the power conversion device of the first vehicle includes the neutral point connection switch, and

the first control circuit of the first vehicle is configured to

turn on the neutral point connection switch in the islanded operation to establish conduction between a neutral point of the AC-side input/output end of the power conversion device and a functional grounding line at a chassis potential, and

turn off the neutral point connection switch in the grid-interconnection operation or the grid-connected supply operation to disconnect the neutral point of the AC-side input/output end of the power conversion device from the functional grounding line at the chassis potential.

(B6)

A power system comprising:

the power supply apparatus according to (B1);

the vehicle electrically connected to the power supply apparatus via the charge/discharge cable;

the first distribution board provided between the power grid and the power supply apparatus; and

the second distribution board, wherein,

in the grid-connected supply operation or the grid-interconnection operation, a potential difference between the pair of power lines of the AC-side input/output end of the power conversion device of the vehicle is the first voltage, and

in the islanded operation, a potential difference between the pair of power lines of the AC-side input/output end of the power conversion device of the vehicle is the second voltage.

(B7)

The power system according to (B6), wherein

the vehicle is a first vehicle including the power conversion device in which the neutral point connection switch is provided between a neutral point of the pair of power lines of the AC-side input/output end and a functional grounding line at a chassis potential, and

the first control circuit of the first vehicle is configured to

turn on the neutral point connection switch in the islanded operation to establish conduction between the neutral point of the AC-side input/output end of the power conversion device and the functional grounding line at the chassis potential, and

turn off the neutral point connection switch in the grid-interconnection operation or the grid-connected supply operation to disconnect the neutral point of the AC-side input/output end of the power conversion device from the functional grounding line at the chassis potential.